In an effort to extend their scope of offered services, the digital video broadcasting (DVB) organization specified protocols to broadcast data multiplexed along with traditional digital television (DTV) contents. This broadcast of data is termed data casting. Based on the requirements of different applications using data casting, six (6) profiles were specified. These profiles are identified as data piping, data streaming, multi-protocol encapsulation, data carousels, object carousels, and higher protocols based on asynchronous data streams.
The ever growing demand for IP based services required an intermediate layer that handled the incompatibilities between the Internet's IP architecture and the broadcasting protocol architecture of the DVB organization. This intermediate layer is included as one of the profiles in the data casting specification as the multi-protocol encapsulation profile. In the multi-protocol encapsulation profile, OSI layer 3 datagrams are encapsulated into multi-protocol encapsulated (MPE) sections according to the DVB organization's private data Digital Storage Media—Command and Control (DSM-CC) specifications. The MPE sections are then mapped onto a stream of 188 byte MPEG-2 system layer transport stream (TS) packets.
The DVB physical layer protocol differs based on the physical channel that the services are transported on. Consequently, different protocols for satellite (DVB-S), cable (DVB-C) and terrestrial (DVB-T) are specified. DVB-T which was primarily developed for fixed reception with roof-top directive antenna is also found to be efficient for mobile data services, yet not very efficient for small handheld, low powered battery operated terminals. Handheld mobile terminals require specific features from the transmission system serving them. These features include extended receiver battery life, improved RF performance for mobile single antenna reception, counter high levels of noise in a hostile transmission environment, and efficient handover.
DVB-H enhances DVB-T specifications to incorporate the above-mentioned features by including an optional Reed Solomon forward error correction (RS-FEC) computed across MPE section payloads, called MPE-FEC, and time slicing of the MPE and MPE-FEC sections.
In Internet protocol (IP) data casting over digital video broadcast-handheld (DVB-H) protocol, the encapsulation to multi-protocol encapsulated frames with Reed Soloman forward error correction (MPE-FEC) occurs within an IP encapsulator and is therefore beyond the control of a content encoder. Due to the system architecture, a content encoder and an IP encapsulator lack a real-time feedback link that allows the IP encapsulator to govern the exact location of instantaneous decoding refresh (IDR) pictures in an encoded bit stream.
Tune-in delay refers to the time between the start of reception of a broadcast signal and the start of media rendering. One factor in tune-in delay is the time until a media decoder is refreshed to produce correct output samples.